This relates generally to imaging systems, and more particularly to imaging systems with high dynamic range.
Modern electronic devices such as cellular telephones, cameras, and computers often use digital image sensors. Imagers (i.e., image sensors) may be formed from a two-dimensional array of image sensing pixels. Each pixel receives incident photons (light) and converts the photons into electrical signals. Image sensors are sometimes designed to provide images to electronic devices using a Joint Photographic Experts Group (JPEG) format.
Pixels can be characterized by the maximum charge capacity relative to a noise floor (e.g., pixel noise that generates charge even when the pixel is exposed to minimal or no incident light). The ratio of the maximum amount of measurable light intensity or maximum charge capacity to the noise floor may sometimes be referred to as the dynamic range of a pixel. The dynamic range of each pixel is typically predetermined for conventional imagers. However, having a single predetermined dynamic range can result in poor performance for imaging conditions such as when incident light exceeds the maximum measurable light intensity or when the amount of incident light is less than the noise floor of the predetermined dynamic range.